A circulating transport device such as an escalator includes a plurality of endlessly connected steps 9 made of aluminum alloy, each including a tread 2, a pair of right and left yokes 3, 3 and a riser 4, as shown in FIG. 7 and FIG. 8. These steps 9 circulate to transport objects put on the steps 9. Each step 9 has guide rollers 7, 8 attached to the front and back thereof, which guide movement of the step 9.
Circulating transport devices such as escalators undergo generally operation tests to continuously operate under an unloaded condition, and, if necessary, load tests with a weight such as a sand bag put on the step.
In noise tests of a driving machine, noise has been measured under various load conditions changed by a DC motor connected to the output side of the speed reducer (JP 57-137821, A).
However, in load tests of conventional circulating transport devices, although they can be temporarily loaded, it is physically impossible for them to continuously operate while being loaded. Thus, there has been a problem in that it is extremely difficult to verify the durability of the driving system or guide system under a load condition.
Accordingly, an object of the present invention is to provide a step mechanism of a circulating transport device that can undergo load tests to continuously operate with its step being loaded.